Updating Data

UPDATE

The UPDATE statement modifies existing rows in a table:

UPDATE products SET price = 89.99 WHERE name = 'Headphones';

Always include a WHERE clause unless you intentionally want to update every row. Without WHERE, UPDATE modifies all rows in the table.

Updating Multiple Columns

Separate multiple column assignments with commas:

UPDATE products
SET price = 89.99, category = 'Audio'
WHERE name = 'Headphones';

Using Expressions

You can use expressions in SET:

-- Apply a 10% discount to all Electronics
UPDATE products
SET price = price * 0.9
WHERE category = 'Electronics';

-- Increase all Office product prices by $5
UPDATE products
SET price = price + 5
WHERE category = 'Office';

Updating by Primary Key

The most precise and safe way to update a single row:

UPDATE users SET email = 'newalice@example.com' WHERE id = 1;

UPDATE with Subquery

You can use a subquery in the WHERE clause:

-- Update orders for a specific customer by name
UPDATE orders
SET quantity = 3
WHERE customer_id = (SELECT id FROM customers WHERE name = 'Alice');

Checking How Many Rows Were Updated

SQLite does not return affected row counts directly in SQL. In most drivers, you can call changes():

UPDATE products SET price = 99.99 WHERE category = 'Office';
SELECT changes(); -- number of rows affected by the last statement

Your Task

Update the price of the 'Coffee Maker' product to 54.99. Then select all Kitchen products to verify.